Cancer is one of the leading causes of disease, being responsible for 526,000 deaths in the United States each year. For example, breast cancer is the most common form of malignant disease among women in Western countries and, in the United States, is the most common cause of death among women between 40 and 55 years of age (Forrest, 1990). The incidence of breast cancer is increasing, especially in older women, but the cause of this increase is unknown. Malignant melanoma is another form of cancer whose incidence is increasing at a frightening rate, at least sixfold in the United States since 1945, and is the single most deadly of all skin diseases.
One of the most devastating aspects of cancer is the propensity of cells from malignant neoplasms to disseminate from their primary site to distant organs and develop into metastases. Despite advances in surgical treatment of primary neoplasms and aggressive therapies, most cancer patients die as a result of metastatic disease. Animal tests indicate that about 0.01% of circulating cancer cells from solid tumors establish successful metastatic colonies.
Electric fields have been employed in several different types of cancer therapy. Some of these involve radiofrequency or microwave devices that heat the tumor to greater than 43° C. to kill the cells via hyperthermia. Others use pulsed electric fields to permeabilize the tumor cells to allow the introduction of toxic drugs or DNA.
There is an urgent need in the art to treat cancer and other disorders without the use of invasive therapy and chemotherapeutic agents and with little or no effect on the whole animal. We have discovered that ultrashort electrical pulses can be used as a purely electrical cancer therapy that kills tumors and abnormal cells without hyperthermia or drugs.